I am looking to build a pair of speakers to be left and right rears to match, as well as possible, my Cambridge R50s.

Going through my collection of speakers I find some Kef B110 SP1003s and a pair of T27 6353s. I started looking at using them to build either the CS1 or CS1a but as the units are not those originally used it probably won't work to thier best, and the crossovers are quite expensive. I now think it is probably better to reproduce the Kefkit4 or original Cresta.

My big problem is finding the schematics for either, or both, of the SP1007 and A6375 crossovers. Can anyone help me with this, or comment on my plans?_________________Always trying to figure out what will work and what won't!

Since we are talking rear surround loudspeakers, I would dare say the specific details of a matched crossover to the exact drivers and enclosure is not as critical as with front speakers. The rear surrounds get a fraction of the energy of the front speakers and mainly are used to generate envelopment with ambiance. You don't want them "localized" so the output there is very little under normal conditions.

I would use these drivers and the crossover at hand - or easy to reproduce - and mount them on an enclosure as close as possible to the one the selected crossover was made for - which, in the case of the B110 should be anything between 5 - 10lt sealed.

SaSi, thanks for your response, I believed that this was the case, however I have some Quadrophonic recordings that appear to push almost equal volume levels to all 4 corners. No chance of having 4 R50s in the room!

I have just managed to find schematics for KEF's DN13 SP1017 crossover which was used for some of the earlier combinations of the B110 & T27 so am going to try that.

I am always interested in other peoples ideas, so again many thanks._________________Always trying to figure out what will work and what won't!

proffsi, at the moment I am considering all options, have got the sheets on the CS1 & CS1A, I have a pair of the older type B110s and T27s and a pair of brand new Morel CAT 928s. Trying not to spend too much. I am still trying to find a local woodworker who can make me a new baffle for my R50s to fit the newer B139s instead of the racetrack pair currently fitted. Thanks for your ideas._________________Always trying to figure out what will work and what won't!

This is probably not a viable offer but I have a pair of empty KefKit3 baffles sitting in the garage waiting to be taken to the dump. These housed the later B139. One of them has a hole cut in it to house a Coles 4001G (it was a failed experiment).

If there is any way you could collect one of the baffles for a woodworker to use as a template you are more than welcome to it. If it would help, I could probably even cut out the B139 section.

surv1v0r, Thanks for the but probably not viable unless you live in North Derbyshire or are near Hastings next week. A good thought though. I have the KEF template for the driver if I can find someone who is a whizz with a router. Thanks anyway._________________Always trying to figure out what will work and what won't!